Loadcenter busbar retention

ABSTRACT

An electrical consumer unit comprises a moulded plastics baseplate (10) and a cover member (280), the baseplate (10) being adapted to mount a live busbar (24) and a neutral bar (90) to which a main, power-supply switch (196) and a plurality of circuit-breakers (212), for protecting a number of outgoing sub-circuits may be mounted. The unit is particularly intended for use with plug-in type switches and circuit breakers whereby a clip for mounting the switch also establishes electrical connection with the live busbar (24) and neutral bar (90). The present invention concerns an arrangement, comprising mouldings (46 and 48) of the baseplate (10) and a clip member (108), for retaining the live busbar (24) and neutral bar (90) in position.

This invention relates to electrical consumer units and is principally,but not exclusively, concerned with consumer units for domestic use.

As is well known, a consumer unit comprises an enclosure containing aswitch or circuit breaker (usually double-pole) for the incoming supply,a number of outgoing subcircuits each having its live side protected bya fuse or circuit breaker, and means interconnecting the live supplywith the fuses or circuit breakers and interconnecting the neutrals andgrounds.

It is known to provide the live interconnection by means of a busbarengaged by resilient clips on the incoming switch or circuit breaker andon miniature circuit breakers (mcb's) which provide the subcircuitprotection;.

Known consumer units suffer from a number of disadvantages.

One problem area relates to the enclosure itself. This is conventionallyprovided in the form of a box and cover formed from folded sheet metal,usually mild steel. The box has a planar base which is secured to a wallto leave four sides projecting from the wall. The electrical parts aremounted, via insulators where necessary, to the base. Duringinstallation the electrician must feed cables into the box and make therequired connections within it. This can be a difficult operation, andwhile carrying it out it is easy to impose undue stress or over-tightbends on the cables. Such enclosures are of poor aesthetic appearance,since the possible shapes are limited, and sheet edges and joins arevisible. Moreover, consumer units of this type are expensive tomanufacture as they require a relatively large number of parts andassembly operations which are difficult to mechanise.

Frequently, a consumer unit is installed which serves fewer subcircuitsthan are provided for; for example, a six way unit may serve only foursubcircuits, thus leaving two portions of the live busbar bare. It isknown to shroud such portions with insulating material, but shroudshitherto in use are cumbersome and are difficult to position and removewhen the consumer unit is fully assembled.

Plug-on busbar units of the type described above are suitable forreceiving only mcb's. An alternative conventional approach is to mountfuse carriers and/or mcb's on a mounting rail which does not carrycurrent, the interconnections being made via cables or busbars. The DINrail system is commonly used for this purpose. In recent years there hasbeen a trend to use the DIN rail to additionally mount accessories suchas timers and sensor controllers. It has not hitherto been possible tomake use of DIN-mounting accessories and plug-on mcb's in the sameconsumer unit.

Accordingly, it is an object of the present invention (which inventionis defined in the appended claims) to overcome or mitigate at least oneof the foregoing problems.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of the baseplate of a consumer unit embodying theinvention;

FIGS. 2, 3 and 4 are, respectively, end, front and rear views of thebaseplate of FIG. 1;

FIG. 5 is a section on line A--A of FIG. 1;

FIGS. 5A, 5B and 5C are, enlarged fragmentary views of details W, V andZ respectively of FIG. 5;

FIG. 6 is a section on line B--B of FIG. 1;

FIG. 7 is a section on line C--C of FIG. 1;

FIGS. 7A, 7B and 7C are enlarged fragmentary views of details U, X and Yrespectively of FIG. 7;

FIG. 8 is a section on line D--D of FIG. 1;

FIG. 9 is a section on line E--E of FIG. 1;

FIG. 10 is a section on line F--F of FIG. 1;

FIG. 11 is a section on line G--G of FIG. 1;

FIG. 12 is a section on line H--H of FIG. 1;

FIGS. 13A and 13B are, respectively, plan and end views of a live busbarembodying part of the invention;

FIGS. 14A and 14B are, respectively, plan and end views of a neutral barembodying part of the invention;

FIGS. 15A, 15B and 15C are, respectively, side, end and bottom views ofa double-pole switch with which the invention may be used;

FIGS. 16A, 16B and 16C are, respectively, side, end and bottom views ofa single-pole circuit breaker with which the invention may be used;

FIGS. 17, 18 and 19 are, respectively, plan, side and front views of abusbar retaining clip embodying part of the invention;

FIG. 20 is a section on line A'--A' of FIG. 17;

FIG. 21 is a section on line B'--B' of FIG. 17;

FIG. 22 is a greatly enlarged view of a conical pip formed on certainsurfaces of the clip of FIGS. 17, 18 and 19;

FIGS. 23A and 23B are, respectively, plan and side views of a barrierclip embodying part of the invention;

FIGS. 24A and 24B are, respectively, top and side views of a neutralterminal strip embodying part of the invention;

FIGS. 25A and 25B are, respectively, top and side views of an earthterminal strip embodying part of the invention;

FIGS. 26, 27 and 28 are, respectively, plan, end and top views of acover member of a consumer unit embodying the invention;

FIG. 29 is a section on line A"--A" of FIG. 26;

FIG. 30 is a section on line B"--B" of FIG. 26;

FIG. 31 is a plan view of the baseplate of a second consumer unitembodying the invention;

FIGS. 32, 33, 34 and 35 are, respectively, top, bottom front and endviews of a DIN rail adaptor embodying part of the invention;

FIG. 36 is a section on line A'"--A'" of FIG. 32;

FIG. 37 is a section on line B'"--B'" of FIG. 32;

FIG. 38 is a plan view of an escutcheon for installation in the covermember of a consumer unit embodying the invention when the DIN railadaptor of FIGS. 32 to 37 is in use; and

FIG. 39 is a section on line D'--D' of FIG. 38

FIG. 40 is a perspective view of the baseplate FIG. 1 having a busbar,neutral bar, retaining clip and terminal strips (as shown in FIGS. 13,14, 17, 18, 19, 24 and 25) mounted thereon;

FIG. 40a is an enlarged fragmentary view of a portion of the baseplateof FIG. 40, illustrating the location of the barrier clip illustrated inFIGS. 23a and 23b;

FIG. 41 is a perspective view of the single pole circuit breaker ofFIGS. 16a, 16b, and 16c; and

FIG. 42 is a perspective view of the double pole switch of FIGS. 15a,15b and 15c.

Referring firstly to FIGS. 1 to 4 FIGS. 40 to 42 of the drawings, abaseplate, generally designated 10, of a circuit breaker box comprises asubstantially planar, rectangular base 12 formed from plasticsinsulating material and having various formations moulded in the centreof the surface thereof whereby a busbar 24 (FIGS. 13A and B), a neutralbar 90 (FIGS. 14A and B), a plurality of circuit breakers 196, 212(FIGS. 15A, B and C, FIGS. 16A, B and C), terminal strips 238, 242(FIGS. 24A, B and 25A, B) etc may be mounted on the baseplate 10. Thesefeatures are described in more detail below. The base 12 furtherincludes a plurality of apertures 14 located at each corner thereofwhereby it may be affixed to a wall (not shown) or the like by means ofscrews (not shown) or other suitable fixing means, a plurality oflocating lugs 16, 18 disposed around its periphery for locating a covermember (FIGS. 26 to 30) and first and second cover-fixing posts 20located adjacent either lateral edge of the base 12. FIG. 40 showsadditional fixing appatures 14' located adjacent the posts 20. The lugs16, 18 and posts 20 are also moulded integrally with the base 12 and theposts 20 are each provided with a bore 22 (see also FIGS. 6 and 8)extending downwardly from their topmost surfaces 24 to receive a screwor the like (not shown) for fixing the cover member to the baseplate 10.

FIGS. 13A and 13B show a metal busbar 24 (preferably copper) comprisingan elongate strip 26 having a plurality of tongue portions 28, 30, 32,34, 36, 38, 40 spaced along and extending outwardly from one lateraledge thereof, the first tongue 28 being spaced slightly from a first end42 of the strip 26 and the last tongue 40 being spaced from the oppositeend 44 of the strip by a relatively greater distance.

In use, the busbar 24 is supported, spaced from the base 12, at eitherof its ends 42 and 44 by first and second raised mouldings 46 and 48respectively. The first of these mouldings 46 includes a ledge 50 (seealso FIG. 7), recessed from the adjacent portions of the moulding 46,slightly wider than the strip 26 of the busbar 24, and an extension 52which projects at right angles from one side 54 of the ledge 50 (towardsan "upper" edge 56 of the base 12). The second moulding 48 comprises agenerally rectangular box 58, open at its bottom 60 and closed at itstop 62 (see also FIGS. 6 and 8). One wall 64 of the box 58 which facesthe centre of the board 12 and the first moulding 46, defines a shoulder66, and a slot 68 adjacent the shoulder 66 and extending across thewidth thereof which communicates with the interior of the box 58. Inuse, the second end 44 of the busbar 24 is inserted into the slot 68 andrests upon the shoulder 66, and the first end rests upon the ledge 50.The tongue 28 of the busbar 24 is supported by the extension 52projecting from the ledge 50. The busbar 24 thus extends transversely ofthe base 12 with the tongues 28 to 40 projecting towards the top edge56.

A further raised moulding 70 located adjacent the moulding 46 alsoincludes a ledge 72 (see also FIG. 8) and an extension 74, of the sameheights and widths as the ledge 50 and extension 54, the extensions 54and 74 being parallel to one another. The extension 74, however, extendsto meet a moulded rail 76 which extends transversely of the base 12 (ieparallel to the busbar 24 when in position) between the mouldings 46,48, 70 and the edge 56.

As is best seen in FIGS. 5, 6 and 7, the rail 76 comprises a wall 78,having a relatively low portion 80 and a relatively high portion 82,(the portion 82 having a "front" face 84 which faces the tongues 28 to40 of the busbar 24 when in position), and a shoulder 85 extending alongthe "rear" face 86 of the wall 78. A notch 88 (FIG. 10) is formed in theportion 80 of the wall 78 and the surface of the shoulder 84 oppositethe extension 74 of the ledge 72. The purpose of this and other featuresof the rail 76 is explained below.

The ledge 72 and extension 74 support a neutral bar 90 which, as shownin FIGS. 14A and 14B, comprises a short strip 92, of the same width asthe strip 26 of the busbar 24, and a tongue 94. The tongue 94 comprisesa first portion 96 extending from an edge 98 of the strip 92, and of thesame width as the tongues 28 to 40 of the busbar 24, and a relativelywider end portion 100 having an aperture 102 formed therein. In use, thestrip 92 rests on the ledge 72, the first tongue portion 96 is supportedby the extension 74 and the end tongue portion 100 extends into thenotch 88, the aperture 102 being aligned with a bore 104 extendingdownwardly from the floor 106 of the notch 88 (see FIG. 10).

The busbar 24 and neutral bar 90 are retained in place on the base 12 bymeans of a clip 108, preferably of plastics material, as illustrated inFIGS. 17 to 22. The clip 108 comprises an elongate member 110 havingfirst, second and third arms 112, 114 and 116 extending outwardly atright angles from either end and from the middle thereof respectively.Each of the arms 112, 114 and 116 has a tooth 118 projecting downwardlyfrom its outer end, each tooth being split transversely by a slot 120and having a barb 122 formed at the bottom of its outermost face 124.The second and third arms 114 and 116 are each additionally providedwith a barrier portion 126 extending along one side (the right hand sidein FIG. 21) of the lower surface 128 thereof. The barrier portions 126are approximately half the width of the arms 114 and 116 and of the samedepth as the teeth 118, and extend from the inner faces of the teeth 118part-way along the arms 114 and 116 towards the elongate member 110.

The clip 108 is further provided with first, second and thirdprojections 130, 132, and 134 formed on a face 136 of the elongatemember 110 opposite that from which the arms 112, 114 and 116 project.As is best seen in FIGS. 18 and 20, each of the projections 130, 132,134 comprises a first face 138 extending "upwardly" from the bottom edgeof the face 136 at a first angle (typically 45° to the horizontal asillustrated) and a second face 140 extending from the end of the firstface 138 at a second angle (typically 70° to the horizontal). Smallconical pips 142 (shown greatly enlarged in FIG. 22) are also formed onthe underside 144 of the elongate member 110, mideway between the arms114 and 116, and on the undersides 146, 128 of the arms 112, 114, 116,adjacent the barrier portions 126 of arms 114 and 116 and in acorresponding position on arm 112. Finally, the clip 108 is providedwith a pair of triangular lugs 148, 150 extending upwardly from theouter arms 112, 114, each of said lugs 148, 150 being provided with aprojection 152, 154 on its inner face 156, 158 at the apex thereof. Theprojections 152, 154 are in the form of circular wedges thickening in adownward direction.

As mentioned above, the clip 108 serves to retain the busbar 24 andneutral bar 90 in position on the base 12 and, as is best seen in FIG. 1and FIGS. 7 to 11, suitable formations are moulded in the surfacethereof around the ledges 50 and 72 to receive the clip 108. Theseformations comprise a shoulder 160 extending along the front face 162 ofthe portion 80 of the wall 78 and first, second and third arms 164, 166,168 extending at right angles from either end and from the middle of theshoulder 160 respectively, the spacing of the arms corresponding to thespacing of the arms 112, 114, 116 of the clip 108. The arms 164, 166,168 extend beyond the ledges 50 and 72 and terminate with block portions170, 172, 174. The upper surfaces of the shoulder 160, the arms 164,166, 168 and the block portions 170, 172, 174 are raised above the levelof the ledges 50 and 72 by a distance corresponding approximately to thethickness of the busbar 24 and the neutral bar 90.

As is best seen in FIGS. 7B and 7C, first, second and third slots, 176,178, 180 are formed in the face 162 of the wall portion 80 immediatelyabove the shoulder 160, and first, second and third downwardly extendingapertures 182, 184, 186 are formed in the block portions 170, 172, 174.In use, the slots 176, 178, 180 receive the projections 130, 132, 134 ofthe clip 108 and the apertures 182, 184, 186 receive the teeth 118. Eachof the apertures 182, 184, 186 includes an inwardly extending lip 188and a shoulder 190 (see FIG. 7B). Upon insertion of the teeth 118 intothe apertures 182, 184, 186, the barbs 122 of the teeth 118 engage underthe lips 188 and retain the clip 108 in place so that it may not beremoved without considerable difficulty.

It will be noted that the arms 164, 168 which extend adjacent the ledges50 and 72 are cut away along part of their length to accommodate thebusbar 24 and neutral bar 90. The other arm 166 is cut away in a similarmanner. This is not strictly necessary in the embodiment of FIG. 1,however, as will be described later, it is useful in other applicationsfor which the same or a similar moulding is employed. The arms 168 and166 and block portions 174 and 172 further include cut-outs 192 and 194to accommodate the barrier portions 126 formed on the arms 114 and 116of the clip 108.

When the busbar 24, neutral bar 90 and clip 108 are installed on thebase 12, then, the arms 112 and 116 extend across the busbar 24 andneutral bar 90 to retain them in position. The conical pips 142 of theclip 108 bear upon the surfaces of the busbar 24 and neutral bar 90 torestrict their movement when clamped in place, whilst the barrierportion 126 of arm 116 serves to isolate the neutral bar 90 from thebusbar 24.

The baseplate 12 is particularly intended for use with plug-in typecircuit breakers of the type illustrated in FIGS. 15A, B and C and FIGS.16A, B and C and FIGS. 41 and 42. FIGS. 15A, B and C and FIG. 42 show adouble-pole switch 196 comprising two ganged switches (not shown) in acommon casing 198 and operable by a common actuating member 200. Thecasing 198 is provided with first and second C-clips 202, 204 adjacentone end of its bottom surface 206 and third and fourth C-clips 208, 210adjacent the opposite end thereof. The limbs of the first and secondC-clips 202, 204 are spaced transversely relative to the surface 206whilst the limbs of the third and fourth C-clips 208, 210 are spacedlongitudinally relative thereto; that is, the third and fourth C-clips208, 210 are oriented at right angles to the first and second C-clips202, 204. FIGS. 16A, B and C and FIG. 41 show a single pole circuitbreaker 212 having first and second C-clips 214, 216 located at eitherend of the bottom surface 218 of its casing 220, again oriented at rightangles to one another. The baseplate 10 of FIG. 1 is designed toaccommodate a double-pole switch such as 196, the first and secondC-clips 202, 204 whereof are metallic and constitute neutral and liveterminals respectively, and up to six single pole circuit breakers suchas 212, the first C-clip 214 whereof is also metallic and constitutesits live input terminal.

In use, the first C-clip 202 of the double-pole switch 196 engages thefirst tongue portion 96 of the neutral bar 90, and its second C-clip 204engages the first tongue 28 of the busbar 24, simultaneously affixingthe circuit breaker 196 thereto and establishing electrical connection.When the double pole switch 196 is installed, the projections 152, 154of the lugs 148, 150 of the clip 108 engage apertures (not shown) on theside faces of the switch 202. These aperatures are a standard rivetposition on the Square D Company's range of switches with which thebaseplate 10 is intended to be used. The first C-clip 214 of each of thesingle pole circuit beakers 212 may be attached to one of the remainingtongues 30 to 40 of the busbar 24 in a similar manner.

The third and fourth C-clips 208, 210 of the two pole circuit breaker196 and the second C-clips 216 of the single pole circuit breakers 212,which do not act as terminals of the circuit breakers 196 and 212 andmay be made from plastics material, are attached to the base 12 by meansof a row of raised bosses 222 spaced from and extending parallel to therail 76 at positions opposite the positions of the various tongues 96and 28 to 30 of the neutral bar 90 and the busbar 24.

Each of the bosses 222 comprises a pair of upstanding, parallel, spaced,triangular lugs 224 and 226 having their apices interconnected by asolid, circular section member 228 (FIGS. 5 and 5A) to which theappropriate C-clips 208, 210 and 216 may be attached. The angles anddimensions of the lugs 224 and 226 are selected to allow the circuitbreakers 196, 212 to be levered off against the edges 230 of the lugs224 and 226 remote from the rail 76 when it is necessary to remove them.This helps to reduce the stress placed on the base 12 during suchremoval.

Adjacent lugs 224 and 226 of adjacent bosses 222 are joined by webs 232,and the base is further strengthened by a series of parallel ribs 234and 236 extending, respectively, between the block portions 170, 174 andthe bosses 222 and between the portion 82 of the wall 78 and the bosses222.

The double-pole switch 196, when installed on the base 12, serves as amain input supply switch through which power is fed to the busbar 24.Single pole circuit breakers 212 of appropriate current ratings, whichare also connected to the busbar 24, may then feed up to six branchcircuits. The neutral lines of the branch circuits may be connected to afirst terminal strip 238 (such as is shown in FIGS. 24A and B) which, inuse, is mounted on the shoulder 85 of the rail 76 adjacent the left handend 240 (as seen in FIG. 1) thereof. The first terminal strip 238 isfixed in place by means of a screw (not shown) extending therethroughand entering the aperture 102 of the neutral bar 90 and the bore 104formed in the floor 106 of the notch 88. The strip 238 is thuselectrically connected to the neutral bar 90 and hence to the neutralpole of the double-pole switch 196. The necessary earth connections maybe made via a second terminal strip 242 (such as is shown in FIGS. 25Aand B) mounted towards the opposite end 244 of the shoulder 85 of rail76 by means of a further screw (not shown) and a second bore 246 formedin the floor 248 of the shoulder 85. The neutral and earth terminalstrips 238 and 242, when installed, are electrically isolated from oneanother by a barrier portion 249 extending from the rear of the wall 82across the width of the shoulder 85.

Partially cut out rectangular knock-out portions 250 (see, for example,FIG. 7A) are also formed at appropriate positions on the base 12 whichmay be removed as required to allow wiring (not shown) to pass throughthe base 12 for connection to the various terminals.

If less than six branch circuits are to be supplied (ie. if less thansix single pole circuit breakers 212 are installed), then the exposedportions of the busbar 24 may be shielded against accidental contact bymeans of barrier clips 252 (see FIGS. 23A and 23B) formed from flexible,plastics, insulating material. The barrier clips 252 each suitablycomprise a strip of relatively thin plastics material, of widthsubstantially equal to the width of the single pole circuit breaker 212,and having first and second tongue portions 254 and 256 formed at eitherend 258,260 thereof. The base 12 is adapted to receive the clips 252 bythe provision of a first series of slots 262 and shoulders 264 on thefront face 84 of the wall portion 82 of the rail 76, at positionsopposite the positions of the tongues 32 to 40 of the busbar 24 (wheninstalled), and a second series of slots 266 formed in the base 12intermediate the position of the busbar 24 (when installed) and thebosses 222, directly opposite the first slots 262. The slots 262 and 266and the shoulders 264 are shown in section in FIGS. 5, 5B and 5C. As isbest seen in FIG. 5B, the second slots 266 extend generally diagonallythrough the base 12, being inclined downwardly away from the rail 76.

The barrier clip 252 is installed on the base 12 by inserting the firstand second tongue portions 254, 256 into corresponding first and secondslots 262 and 266 such that the barrier clip 252 assumes an arcuateconfiguration curving over the corresponding portion of the busbar 24(when installed) as shown by the dotted line 268 of FIG. 5. The barrierclip 252 thus shields a portion of the busbar 24 corresponding to thewidth of one single pole circuit breaker 212. Cut away portions 270 and272 are formed adjacent the second end 260 of the barrier clip 252 toallow it to enter between a pair of ribs 236. It will be noted also thatthe slots 262 and 266 and the shoulder 264 are omitted from the part ofthe base 12 corresponding to the position of the second tongue 30 of thebusbar 24 since it is assumed that at least one single pole circuitbreaker 212 will always be installed.

Referring to FIGS. 26-30, the cover member generally designated at 280comprises a top surface 282 and side walls 284 providing a generally boxshape. In use the free edges 286 of the side walls seat against the base12 and are located by the lugs 16, 18 and a peripheral rib therebetween.The top surface 282 has a rectangular opening 290 dimensioned to receivethe upper parts of the circuit breakers mounted in the unit, as is wellknown per se. As best seen in FIG. 29, bosses 292 (jointed to the sidewall 284 by webs 294) are formed integrally and provide bores forfastening screws (not shown) engaged in the bores 22 of the base memberbosses 20 (FIG. 8).

Each side wall 284 is provided with a plurality of knock-out portions296 formed by zones of reduced thickness. The disposition is such thateach knock-out portion 296 is between a pair of the base lugs 16, 18when the unit is assembled. The dimensions of the knock-out portions 296are chosen to receive standard trunking sizes. It will be seen that, inthis embodiment, the knock-out portions 296 extend to the free edge ofthe side wall 284.

Thus, the present consumer unit has a generally planar base member and agenerally box-shaped cover. When making an installation, the base memberis secured in position (having first removed the appropriateknock-out(s) 250 if rear cable entry is to be used). It is then possibleto locate circuit breakers, install the required cabling, and generallycomplete the installation without being hindered by side walls of theenclosure. Once this is complete, the cover can be positioned, havingfirst removed the appropriate knock-out(s) 296 for side cable entries,as a final step.

Turning to FIGS. 32 to 37, there will now be described an adaptor,generally designated 300, for use with the foregoing base and cover. Thepurpose of the adaptor 300 is to provide a means of securing a mountingrail within the consumer unit. The mounting rail may for example be tothe Deutsche Industriale Normalien (DIN) standard, and will be referredto simply as a DIN rail. Standard components for mounting on a DIN railare not designed for engaging a busbar, and have dimensions different tothe Square D Company plug-on miniature circuit breakers for which theembodiment already described is particularly intended.

The adaptor 300 is an integral plastics moulding having a planar body302 and end walls 304. A plurality of lugs 306 project from one side;these are spaced and dimensioned to be engageable in the slots 262. Acorresponding number of resilient clip portions 308 project from theunderside of the body 302 to be engageable on the bosses 222. Theadaptor 300 can thus be removably mounted to the base. In thiscondition, as indicated in broken lines in FIG. 36, the busbar 24 sitsunder the body 302, and the adaptor 300 is braced against the surface ofthe base 12 by projecting parallel, transverse ribs 310. The ribs 310extend across the width of the body 302 and are provided with notches324 to accommodate the ribs 236 of the base 12. FIG. 36 also shows inbroken lines a DIN rail 312 which is secured to the adaptor 300 byfasteners (not shown) engaged in bores 314. The DIN rail 312 is locatedon the adaptor 300 by slots (not shown) in the DIN rail engagingprojections 316 on the surface of the adaptor.

The adaptor 300 shown in the drawings is dimensioned to fit over sixways of a consumer unit. It will be understood that this size of adaptorwould normally be used with a larger consumer unit, eg a 10-way unit, sothat the eventual installation would comprise a number of sub-circuitminiature circuit breakers mounted on the busbar, the adaptor, and anumber of accessories mounted on the adaptor DIN rail.

The spacing of the planar body 302 from the base 12 is chosen such thatthe fronts of the DIN accessories are positioned in the opening 290 inthe cover member 280. Since the accessories have a smaller frontal areathan the circuit breakers, a plastics escutcheon 318 (FIGS. 38 and 39)may be snap-fitted into the opening 290 to provide an aperture 320 ofthe correct dimension D. The cover member is formed with ribs 322 at theperiphery of the opening 290 for engagement by teeth 324 mouldedintegrally with the escutcheon 318.

Turning to FIG. 31, there is shown a modified base 12' arranged tosupport two live busbars. For this purpose, the moulding 46 isduplicated at 46'. One busbar can be mounted between 46 and 46', and theother between 46' and the moulding 48. Clips 108 as described above canbe used in both locations to retain the busbars. Other details of thisembodiment are similar to the foregoing embodiment, and will thereforenot be described in detail. It is contemplated that this double busbararrangement can be used in two ways:

(i) As a consumer unit for two separate supplies serving separatesubcircuits, eg normal tariff and off-peak tariff supplies. In this caseeach busbar would have a separate supply with separate double-poleswitches or circuit breakers mounted on the mouldings 46 and 46'.

(ii) As a consumer unit for a single supply in which a number ofsubcircuits have common earth-leakage protection. In this case, power isfed from the supply via a double-pole switch at 46, the live supplyingthe first busbar, which may supply some subcircuits via normal mcb's;however the second busbar is connected to the live supply via a link andan earth-leakage breaker mounted on the second busbar. Thus, earthleakage protection can be provided for a plurality of circuits in acost-effective manner.

It will be appreciated that whilst the unit previously described withreference to FIGS. 1 to 30 is a six way unit, the features thereof maybe incorporated in larger or smaller units, two to eighteen way unitsbeing a typical range. Furthermore, the mouldings 46 and 48 forsupporting/retaining the busbar 24, the bosses 222 for receiving thecircuit breakers, etc may be moulded as independent units for mountingon a separate base. Other modifications and variations will be apparentto those skilled in the art.

I claim:
 1. An electrical consumer unit comprising:an enclosure formedby a base and a cover; a live busbar; means for mounting a plurality ofelectrical protection devices so as to be fixed in relation to the baseand in electrical connection with the busbar;characterised by means formounting and retaining said live busbar on the base, comprising: a bosshaving an aperture dimensioned to receive one end of the live busbar; anupstanding formation having a shoulder portion for receiving the livebusbar adjacent its other end; and means engageably receiving a clipmember to trap the live busbar between said formation and said clipmember.
 2. The consumer unit of claim 1, in which said upstandingformation is further provided with:a recess for receiving a neutral bar;and the clip member is provided with guide surfaces for receivablylocating an input switching device having resilient connectorsengageable with the live busbar and neutral bar.
 3. The consumer unit ofclaim 1 wherein said live busbar mounting and retaining means aremoulded from an insulating material integrally with said base.
 4. Theconsumer unit of claim 2, in which the clip member includes anintermediate portion acting as an insulating partition between saidother end of the live busbar and the neutral bar.
 5. The consumer unitof claim 2 in which the clip member further includes upstanding sidewebs each provided with an inward-facing projection for engagement witha bore in the input switching device.
 6. The consumer unit of claim 1,in which the clip member includes at least one projection provided witha detect tooth, and said upstanding formation includes a boss defining abore for receiving said projection and an internal shoulder formedwithin the bore for engagement by the detent tooth.
 7. The consumer unitof any of claims 2, in which the base is further formed to provide achannel for receiving a neutral connector block in a position overlyinga free end of the neutral bar.
 8. The consumer unit of claim 7, in whichsaid channel extends to receive a ground connector block, the base beingformed to provide an insulating partition across said channel betweenthe neutral and ground connector blocks.
 9. The consumer unit of claim8, in which the base is further formed to provide a partition wallbetween said channel and the space occupied by the input switchingdevice, the live busbar and the protection devices.
 10. The consumerunit of claim 9, in which said partition wall is provided with at leastone slot engageable by a lug on the clip member.
 11. The consumer unitof claim 1 in which the base is formed to provide, parallel to saidbusbar, a mounting formation, and said electrical protection devices areminiature circuit breakers provided with resilient means for engagingthe live busbar and means for engaging said mounting formation.
 12. Theconsumer unit of claim 11, in which said circuit breaker engagementmeans is a C-shaped clip, and in which mounting formation comprises, foreach miniature circuit breaker location a cylindrical member forengagement by the C-shaped clip, the cylindrical member being supportedabove the major surface of the base by upstanding end walls.
 13. Theconsumer unit of claim 12, in which said end walls extend to that sideof said cylindrical member away from the live busbar at an angle to themajor face of the base, so as to provide an abutment for engagement bythe respective miniature circuit breaker when the latter is pivotedabout the cylindrical member to disengage from the live busbar, furtherpivotal movement against said abutment forcing the C-shaped clip off thecylindrical member.
 14. A consumer unit as claimed in claim 1 includingmeans for mounting and retaining a second live busbar and a secondplurality of electrical protection devices adjacent said first mountingand retaining means.